To evaluate the neonatal and maternal outcomes in obese pregnant women whose weight gain differed from Institute of Medicine (IOM) recommendations.
We conducted a retrospective study of maternal and neonatal data from 12 hospitals to examine the effects of weight change during pregnancy in obese women (body mass index [BMI, calculated as weight (kg)/[height (m)]2] 30 or greater; N=10,734). Using a 1:1:1:1 design (n=488 matched groups), we matched obese women who lost weight, maintained weight, gained appropriate weight (IOM-recommended) and gained excessive weight during pregnancy by gestational age at delivery (less than ±1 week) and maternal characteristics of age (less than ±1 year), race and ethnicity, BMI (±10%), chronic hypertension, pregestational diabetes, and smoking status. Generalized estimating equations were used to examine the effects of pregnancy weight change on maternal and neonatal outcomes.
Compared with IOM recommendations, weight loss was associated with increased odds of small-for-gestational-age (SGA) birth (odds ratio [OR] 1.73 [1.11–2.70]; P=.013). Losing weight (OR 0.59 [0.37–0.94]; P=.029) and maintaining weight (OR 0.61 [0.38–0.98]; P=.040), however, decreased the odds of gestational hypertension. Gradual change in outcomes from lost to excessively gained weight revealed 1.4 times greater odds of cesarean delivery, a threefold increase in odds of gestational hypertension, and doubled odds of neonatal intensive care unit admission with increasing weight gain. In contrast, the odds of SGA increased 2.5 times with decreasing weight gain or weight loss.
Weight loss in obese pregnant patients increases the risks of SGA neonates; however, it does not increase neonatal morbidity and decreases maternal morbidity.